Veneer stacker

ABSTRACT

Apparatus for sorting and stacking veneer sheets comprising a vacuum infeed conveyor transporting individual sheets of veneer width-wise to a position above a scissors lift table whereupon parallel-motion knockdown arms are actuated to force the sheet loose from the vacuum conveyor and down onto the top of a pile forming on the lift. Squaring of the pile of sheets into a uniform stack is accomplished by the knockdown arms which move the forward lateral edge of the sheet up against a fixed stop acting in conjunction with a pair of actuatable even-ender pusher arms which align the longitudinal edges of the sheet. When a predetermined pile height is reached, as determined by the downward indexing of the scissors lift, the completed pile is discharged from the apparatus by an outfeed conveyor. While the pile is being discharged a pair of accumulator members are moved into position beneath the knockdown arms so as to temporarily support and retain the initial several sheets of a new pile as the scissors lift is discharged and recycled to the position where it is ready to receive the new pile in formation. A modification of the apparatus provides one or more additional bin locations adjacent the first bin location to receive and segregate the veneer sheets into stacks according to size or other criterion.

United States Patent [451 Oct. 17, 1972 Brawn [54] VENEER STACKER [72]lnventor: Philip E. Brawn, Springfield, Oreg.

[73] Assignee: Carothers Sheet Metal Company,

Eugene, Oreg.

[22] Filed: Jan. 18, 1971 [2i] Appl. No.: 107,319

[52] U.S. Cl ..271/74 [51] int. Cl. ..B65h 29/32 [58] Field of Search..209/82; 271/74, 88, 89

[56] References Cited UNITED STATES PATENTS 1,942,]72 l/l934 Johnson..271/88 3,227,275 l/1966 Cody ..27ll74 X 3,298,683 l/l967 Stroud..271/88 x 3,305,233 2/1967 Cody ..27ll74 3,490,764 l/l970 M'tieller..27ll74 3,583,562 6/1971 Yock ..271/74 Primary Examiner-Richard A.Schacher [5 7] ABSTRACT Apparatus for sorting and stacking veneersheetscom:

prising a vacuum infeed conveyor transporting individual sheets ofveneer width-wise to a position above a scissors lift table whereuponparallel-motion knockdown arms are actuated to force the sheet loosefrom the vacuum conveyor and down onto the top of a pile forming on thelift. Squaring of the pile of sheets into a uniform stack isaccomplished by the knockdown arms which move the forward lateral edgeof the sheet up against a fixed stop acting in conjunction with a pairof actuatable even-ender pusher arms which align the longitudinal edgesof the sheet. When a predetermined pile height is reached, as determinedby the downward indexing of the scissors lift, the completed pile isdischarged from the apparatus by an outfeed conveyor. While the pile isbeing discharged a pair of accumulator members are moved into positionbeneath the knockdown arms so as to temporarily support and retain theinitial several sheets of a new pile as the scissors lift is dischargedand recycled to the position where it is ready to receive the new pilein formation. A modification of the apparatus provides one or moreadditional bin locations adjacent the first bin location to receive andsegregate the veneer sheets into stacks according to size or othercriterion.

2 Claims, 9 Drawing Figures PATENTEDucI 17 m2 SHEET 1 [1F 4 PATENTEDucI11 m2 SHEET 2 [IF 4 FIG. 1A

FIG.

PMENTEDIJBI 1 I972 sum 3 BF 4 FIG. 2

VENEER STACKER BACKGROUND OF THE INVENTION This invention relates toimprovements in a veneer stacker for stacking individual sheets or pliesof veneer into a uniform pile, and thereafter outfeeding the pile soformed so that it can be strapped, transferred to a dolly or forklifttruck or otherwise handled for further processing. More specifically,the veneer stacker of the present invention provides improved means forensuring that a uniformly-aligned stack of veneer is formed and that theoperation of the infeed supplying individual sheets of veneer to thestacker apparatus is not delayed or interrupted while a completed stackof veneer is discharged from the apparatus. Additionally, a modificationof the invention extends the apparatus to cover a plurality of binlocations so that veneer sheets fed into the apparatus can be sorted andstacked according to size, grade, moisture content or other criteria forsegregation.

Devices for sorting and stacking veneer sheets or plies as they arereceived from the dryer or the green chain end of the clipper of aveneer line are known to the art and shown for example in Stickney U.S.Pat. No. 3,508,648 and Keller U.S. Pat. No. 3,540,567. Generallyspeaking, the major difficulties encountered with prior artsorters/stackers of the type described are that (1) they do notsatisfactorily align the sheets both longitudinally and laterally so asto form a satisfactorily squared-up stack, and (l) the operation of theapparatus must be interrupted or slowed down, or alternatively anadditional holding bin location provided, while a completed stack isremoved from the apparatus. Accordingly, a real need exists in theforest products industry for a veneer stacker which will consistentlyand reliably form individual sheets of veneer into a uniformly-alignedstack which can thereafter be removed from the apparatus in a mannerwhich will avoid disruption or slow-down of the production line.

SUMMARY OF THE PRESENT INVENTION The present invention is directed to aveneer stacker of the general type described in which a vacuum infeedconveyor transports individual sheets of veneer along their lateral(i.e., transverse-to-the-grain) dimension to a position above a scissorslift table whereupon parallel-motion knockdown arms are actuated toforce the sheet loose from the conveyor and down onto the top of a pileforming on the lift table. Even-ending pusher arms acting on thelongitudinal (parallel-to-the-grain) sides of the veneer sheet, inconjunction with the parallel-motion knockdown arms and an anti-kickbackelement for receiving and holding the forward lateral edge of the veneersheet, ensure uniform longitudinal and transverse alignment of eachsheet delivered onto the stack. Accumulator means in the form ofactuatable arm elements are provided for temporarily supporting theinitial several sheets forming a new pile while the previously-formedstack of veneer is discharged from the apparatus so as to thereby avoidthe necessity for interrupting or slowing down the operation of theapparatus, or alternatively providing a temporary holding bin locationwhile a completed stack is removed. In a modification of the apparatus,additional in-line bin locations are provided, each capable of forming astack of veneer from sheets of predetermined size, so as to provide asorting capability for the apparatus wherein veneer sheets infeeding tothe apparatus of diverse size, grade, moisture content, or othercriteria can be segregated according to the sorting criteria and stackedinto uniform piles.

It is therefore a principal objective of the present invention toprovide a new and improved stacker for veneer sheets and like materialwhich is of economical design, minimizes the possibility of damage ordegrade of the veneer in the stacking process, builds up a more compactand uniformly-aligned pile, and provides means for rapidly discharging acompleted stack without disrupting or delaying the regular flow ofmaterial infeeding into the apparatus.

It is a principal feature of the present invention to provide a veneerstacker of the type described wherein accumulator means are provided fortemporarily supporting and retaining the initial group of sheets formingthe beginning of a new pile while the completed pile previously formedis outfed from the apparatus.

It is a further feature of the present invention to provide in a stackerapparatus of the improved type described means for sorting theindividual veneer sheets according to one or more criteria such as size,species, moisture content and the like and thereafter stacking them intouniform piles at designated bin loca tions.

The foregoing and other objectives, features and advantages of thepresent invention will be more readily understood upon consideration ofthe following detailed description of the invention, taken intoconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view ofan illustrative embodiment of the veneer stacker of the presentinvention with the accumulator elements shown in the operative position.

FIG. 1A is an end sectional view of the main portion of the veneerstacker with the accumulator element shown in the retracted position.

FIG. 2 is a side elevational view of the veneer stacker, with theoutfeed conveyor mechanism removed for the sake of clarity.

FIG. 3 is a top plan view of the veneer stacker.

FIG. 4 is a detail sectional view of one of the vacuum infeed conveyorbelts taken along the line 4-4 in FIG. 3.

FIG. 5 is an underview of the vacuum conveyor belt taken along the line5-5 in FIG. 4.

FIG. 6 is an enlarged side view showing details of the knockdown armmechanism of the veneer stacker.

FIG. 7 is an enlarged end view showing details of the accumulatormechanism.

FIG. 8 is a partial side elevational view showing a modified form ofaccumulator mechanism for use with a one or two-bin capacity veneerstacker.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings,particularly FIGS. 13 initially, an exemplary embodiment of the veneerstacker apparatus comprises a skeletal framework of metal girders andtubing 11 defining two respective bin locations 12, 14 for the stackingof veneer into two piles segregated according to size or other criteria.Illustratively, the sorting may be on the basis of width with the firstbin location 12 receiving sheets of 54-inch width and the second binlocation 14 receiving sheets of 27- inch width, which sizes are thestandard sheet widths employed in the domestic veneer industry forfaces, centers and backs in the lay-up of veneer into 4-by-8 footplywood panels.

The stacker apparatus is typically located to receive veneer sheetsdirectly from either a veneer dryer or the green chain end of a veneerproduction line. The infeeding of veneer into the entry end of thestacker is accomplished with a vacuum conveyor 16, the details of whichare described hereinafter, which transports the individual sheetswidth-wise along their transverse-tothe-grain dimension, by theapplication of negative pressure or suction to the top surface thereof,to a position directly above the designated bin location 12 or 14,depending upon the size of the veneer sheet. At this point a pair ofknockdown arms 18 is actuated by the tripping of limit switch 29a topress the veneer sheet loose from the vacuum conveyor and force thesheet downward and forward until its leading lateral edge (see FIG. 6)abuts against a fixed stop 50. The sheet is retained in abuttingposition against the stop 50 by means of a spring-biased serrated jawelement 22a attached to the frame and pressing downward on the forwardedge of the veneer pile to prevent kickback of the sheet after it hasbeen brought against the rest 50. A pair of auxiliary spring armelements 24 having a vertically-depending leg 24a assist in maintainingthe the veneer sheet in as the stack is formed.

Immediately after the veneer sheet is removed from the conveyor infeed16 by the action of the knockdown arms 18, the longitudinal(parallei-to-the-grain) edges of each veneer sheet 28 is aligned by theenergization of actuators 30a operating even-ender pusher arms 30 which,through a time delay after the tripping of limit switch 29,simultaneously retract and then move inwardly toward each other to alignthe veneer sheet therebetween. After the veneer has been pushed underthe anti-kickback jaw 22, and up against the stop 50 the even-enderpusher arms 30 remain in the extended position bearing against thelongitudinal edges of the top plies in the stack thus retaining theveneer sheets in a uniformly-aligned pile as additional sheets areadded.

The veneer stack 28 is supported on a scissors lift table 23 whichindexes downward, upon triggering of limit switch 47, in regularincrements as the pile builds up. The top of the scissors lift table 23is formed of a plurality of spaced free-turning rollers 25 alignedparallel to the lateral or short dimension of the sheet to facilitatelengthwise removal of the completed stack of veneer from the side of theapparatus.

When the lift table 23 has indexed downward to a point where a pile ofpredetermined height (e.g., 30 inches) has been formed, limit switch 39is thereupon triggered, causing the scissors lift to continue downwarduntil it bottoms out and at the same time bringing into position beneaththe infeed conveyor 16 the arms 35 of an accumulator mechanism, thedetails of which are hereinafter described, for receiving andtemporarily supporting the initial group of sheets of a new pile ofveneer while the previously-formed stack 28 is removed automaticallyfrom the bin location.

(During the time the veneer is being temporarily stacked on theaccumulator limit switch 42 is maintained triggered which deactivateslimit switch 47 controlling the indexing of the scissors lift table 23.)Discharge of the completed stack after the scissors table 23 hasbottomed out is effected by actuation through limit switch 45 of thedrive 40 of an endless chain conveyor 43 which transports the completedstack 28, along its longitudinal dimension, off of the rollers 25 formedinto the top of the scissors lift and out of the bin area, and thenceonto roller support tables 36 where the completed stack can thereafterbe outfed to another conveyor, or transferred to a forklift truck ordolly, as desired.

As the completed stack of veneer 28 moves away from the bin area itstrailing edge releases limit switch 45 causing the scissors lift table23 to commence rising back upward. The lift table continues rising untilit triggers limit switch 48 which stops the upward movement of the liftand simultaneously causes the respective accumulator arms 35 to move outfrom under the pile of veneer which has been stacked thereon during thetime while the previously-completed load was being lowered anddischarged, and to gently deposit it onto the now fully recycled lifttable.

While the scissors lift is recycling the return to the upward positionto receive the new stack of veneer, the previously-completed pilecontinues to move on the outfeed conveyor 43 until trailing edge of theveneer releases a limit switch 41 and the stack stops, resting on theroller support tables 36.

Returning now to the details of the stacker construction, the vacuuminfeed conveyor 16 comprises a plenum chamber 15 on the top of theapparatus which has a negative pressure created therein by an air blower(not shown). The plenum is connected by ducts 13 on the top periphery ofthe stacker frame 15 to a plurality of air boxes 17 spaced in rowsextending along the direction of travel of the veneer sheets as theyfeed into the apparatus. The bottom of each of these air boxes 17 isperforated with a plurality of small spaced apertures 19. An endlessconveyor belt 20, supported on pulleys 26 and driven by motor 27,travels immediately beneath each of the longitudinally-extending airboxes and is perforated along its length with a corresponding array ofspaced openings 21 so that the veneer sheet 28 is held under vacuum andconveyed by the traveling belts 20.

As previously mentioned, the veneer sheet 28 is carried into theapparatus by the vacuum infeed conveyor 16 until it reaches a positionabove its designated bin location whereupon limit switch 29a is trippedwhich actuates the knockdown arms 18. Referring to FIG. 6, the knockdownarms each comprises a horizontal runner arm 18' which is pivotallysupported for parallel-motion action at two points along its length byarm members 19a, 18b which in turn are pivotally connected to thesupport frame 11. A forwardly projecting spring finger 22 depends fromthe leading edge of the runner 18' to assist in the lateral alignment ofthe sheet into the stack. An extension 18c of one of the swing arms 18::is connected to a pneumatic or fluid-operated actuator 31. The actuatorrod is normally extended so that the knockdown arm 18 associatedtherewith is held elevated above the plane of the conveyor belts 20 inthe non-operative position.

Upon energization of the actuator 31 when limit switch 290 is tripped,the actuator rod retracts, causing the horizontal runner 18' of theknockdown arm 18 to move downward through the plane of the conveyorbelts forcing the veneer sheet loose and onto the top of the veneerstack 28. The parallel-motion movement of the knockdown arm causes therunner to contact the veneer sheet along a substantial length thereof,rather than at just one point, thus ensuring that the sheet ismaintained substantially horizontal as it is deposited by the pair ofconcurrently-acting knockdown arms or to the top of the pile. Thecontinuing downward arcuate motion of the swing arms 18a, 18b abouttheir respective pivot points slides the sheet forward by the action ofthe projecting spring finger 22 until its leading edge abuts against thefixed stop 20. Reversal of the actuator 31 then quickly retracts theknockdown arm 18 back upward beyond the plane of the conveyor belt intothe nonoperative-position ready for the next actuating signal from thelimit switch 290.

In the case of a two-bin sorter handling two different widths of veneer,for example 54 inch sheets and 27 inch sheets, judicious placement of asecond limit switch 29a spaced ahead of limit switch 290 by more thanthe width of the smaller category of sheet and coupled to a coincidentcircuit for triggering the action of the respective knockdown arms 18,may be provided in the first bin location 12 receiving the wider sheets.This will permit the shorter width sizes of veneer sheet to pass overthe first bin location 12 without actuation of its knockdown arms, andonto the second bin location 14 where limit switch 29a (FIG. 2) will betripped for actuating the knockdown arms associated therewith. Theprinciple of coincident limit switches with variable spacing can ofcourse be extended to a multi-bin stacker handling a variety of sheetwidths. Additionally other sorting criteria can be provided, through theuse of memory logic and control devices working with inputscorresponding to thickness, moisture content and the like, to segregateveneer sheets into a plurality of stacks of respectively uniformcharacteristics.

The accumulator mechanism, the details of which are best shown in FIG.7, comprises on each lateral side of a bin location a pair of pivotablearm members 35 formed of a vertical leg portion 35a and a horizontal armportion 35b. The vertical leg portion 35a has its lower end pivotallyconnected to the stationery frame 11 and its upper end pivotallyconnected for limited articulation to the horizontally-extending armportion 35b. An actuator 33, directly connected to one of the pair ofaccumulator arms 35 and coupled to the other of the pair by linkagemechanism 34, provides the means, under control of limit switch 39, formoving the respective arms 35 between the retracted position (shown indotted lines) and the operative position shown. In the retractedposition of the accumulator arms the rod of the actuator 33 is extended,forcing the respective arms outwardly about their pivot points 37 sothat the upward terminus of the vertical leg portion 35a of each of theaccumulator arms bears against the respective side members of theskeletal support frame 1 1. Because of the articulation provided by thepivot 32 between the vertical leg portions 35a and the horizontalportion 35b, each of the accumulator arms may be more fully withdrawnfrom the center of the bin location than if each of the accumulator armswere a rigid member.

Reversal of the actuator 33 swings the pair of actuator arms 35 awayfrom the side walls and into the operative position over thenow-completed pile formed on the lift table 23 where the horizontal armportions 35b of the respective accumulators 35 provide temporary supportfor the initial sheets of a new pile 28 dropping from the conveyor intothe bin location while the stack previously formed therein is removedoff the scissors table. A cam 38 is provided for coaction with anassociated cam follower 38a carried on each of the accumulator arm 35 soas to maintain the sheet support surface provided by the accumulatorarms in a horizontal plane as the respective accumulator arms are movedbetween their operative and non-operative positions. In this manner thepile of veneer sheets forming a new stack is maintained substantiallystationary as the accumulator arms 35 are withdrawn to permit thescissors lift table 23 to move into position and receive the new pile.To effect this the connection in each of the accumulator arms betweenits horizontal arm portion 35b and its vertical leg portion 35a isprovided by a springbiased coupling 32 permitting a short axialdisplacement therebetween so as to enable the support plane formed bythe respective accumulator arms to be maintained fixed in space as eachof the horizontal arm portions 35b is moved between its operative andretracted positions. (In the absence of the cam mechanism and couplingarrangement provided it will be apparent that the support surface formedby the accumulator arms would move vertically as the arms are swungbetween the operative and retracted positions, thus producing acorresponding displacement in the position of the pile 28 which in turnmight interfere with the operation of the knockdown arms 18 or theeven-enders pusher arms 30.)

It will be understood that, for each bin location, a total of four suchaccumulator arms 35 are preferably provided to swing into the center ofthe bin location to provide a temporary support plane for the initialgroup of sheets forming a new pile while the previouslyformed pile isbeing unloaded. If desired, it may be feasible to extend the length ofthe horizontal arm portions 35b of apair of accumulator forsubstantially the full width of the veneer sheet and, by using aconstruction of sufficient load-bearing capacity, accomplish thenecessary support with but a single pair of accumulator arms 35 ratherthan the four depicted in this illustrative embodiment.

FIG. 8 depicts a modified form of accumulator mechanism in which thepivoting arms of the previous embodiment is replaced by a pair ofhorizontallyreciprocable rods 52 extending from associated hydraulicactuator cylinders 54 which are supported by respective girders 53 andmounted onto the adjacent sides of bin frame 11. In this modificationactuation of the respective actuators 54, in response to a controlsignal received as before from the triggering of limit switch 39, causesthe normally-retracted rods 52 to extend across the width of the binstall 12 forming a temporary support plane for the initial group ofsheets 28 of a new pile while the previously-formed stack is dischargedand the lift table 23 recycled. Because of the outward horizontalextension of the actuator cylinders 54 beyond the side of the stackerframe 11 it will usually not be feasible, by reason of space andconveyor length considerations, to utilize this modified form ofaccumulator mechanism except for veneer stackers of only one or two-bincapacity.

The terms and expressions which have been employed in the foregoingabstract and specification are used therein as terms of description andnot of limitation, and there is no intention, in use of such terms andexpressions, of excluding equivalents of the features shown anddescribed, or portions thereof, it being recognized that the scope ofthe invention is defined and limited only by the claims which follow.

What is claimed is:

1. Apparatus for stacking veneer sheets comprising:

a. vacuum infeed conveyor means for horizontally.

transporting individual sheets of veneer by suction applied to theirrespective upper surfaces to a predetermined position above a binlocation area,

b. knockdown arm means actuable to force said respective sheets loosefrom said conveyor and down onto the top of a pile formed of saidsheets, said knockdown arms comprising a horizontal member, pivotallysupported at two points by vertical swing arms so as to move withparallel motion in a vertical arcuate path, and forwardly-projectingspring finger means depending from the leading edge of said horizontalmember to assist in the lateral alignment of the sheet into the stack,said horizontal member and said projecting spring finger contacting thetop surface of said veneer along the substantial length thereof causingeach sheet deposited to be maintained in a substantially horizontalorientation as it is deposited onto the top of said pile of sheets,

c. fixed stop means positioned to contact and terminate the forwardtravel of the leading edge of a sheet deposited on the top of said pileat a predetermined vertical plane location where a lateral edge of saidpile is to be formed, and

d. a spring-biased serrated jaw anti-kickback element contacting theupper surface of said leading edge of a sheet as it is deposited on saidpile and acting to retain it in a horizontal position abutting againstsaid stop until the next sheet is deposited onto said pile.

2. In an apparatus for stacking veneer sheets inside a bin whereinindividual sheets of veneer are horizontally transported to apredetermined position above said bin and then are deposited on top of apile formed of said sheets, and accumulator means are provided fortemporarily supporting the initial sheets of a new pile while acompleted pile of sheets is removed from said bin, the improvementwherein said accumulator means comprises:

a. a pair of support arm members each respectively formed of a verticalleg portion mounted for pivotal movement in a vertical are relative tothe frame of said bin, a horizontal portion, and spring biased couplingmeans-providing limited articulation of said vertical leg portionrelative to said horizontal portion,

. actuator means for moving said support arm members between respectiveretracted and actuated positions, and

c. cam-and-follower means controlling the vertical articulation of saidhorizontal portion of said respective sup ort arm members wherein thepile of veneer shee s deposited and supported thereon are maintained ina horizontal plane at a substantially constant elevation as said supportmembers move between said actuated and retracted positions.

1. Apparatus for stacking veneer sheets comprising: a. vacuum infeedconveyor means for horizontally transporting individual sheets of veneerby suction applied to their respective upper surfaces to a predeterminedposition above a bin location area, b. knockdown arm means actuable toforce said respective sheets loose from said conveyor and down onto thetop of a pile formed of said sheets, said knockdown arms comprising ahorizontal member, pivotally supported at two points by vertical swingarms so as to move with parallel motion in a vertical arcuate path, andforwardly-projecting spring finger means depending from the leading edgeof said horizontal member to assist in the lateral alignment of thesheet into the stack, said horizontal member and said projecting springfinger contacting the top surface of said veneer along the substantiallength thereof causing each sheet deposited to be maintained in asubstantially horizontal orientation as it is deposited onto the top ofsaid pile of sheets, c. fixed stop means positioned to contact andterminate the forward travel of the leading edge of a sheet deposited onthe top of said pile at a predetermined vertical plane location where alateral edge of said pile is to be formed, and d. a spring-biasedserrated jaw anti-kickback element contacting the upper surface of saidleading edge of a sheet as it is deposited on said pile and acting toretain it in a horizontal position abutting against said stop until thenext sheet is deposited onto said pile.
 2. In an apparatus for stackingveneer sheets inside a bin wherein individual sheets of veneer arehorizontally transported to a predetermined position above said bin andthen are deposited on top of a pile formed of said sheets, andaccumulator means are provided for temporarily supporting the initialsheets of a new pile while a completed pile of sheets is removed fromsaid bin, the improvement wherein said accumulator means comprises: a. apair of support arm members each respectively formed of a vertical legportion mounted for pivotal movement in a vertical arc relative to theframe of said bin, a horizontal portion, and spring-biased couplingmeans providing limited articulation of said vertical leg portionrelative to said horizontal portion, b. actuator means for moving saidsupport arm members between respective retracted and actuated positions,and c. cam-and-follower means controlling the vertical articulation ofsaid horizontal portion of said respective support arm members whereinthe pile of veneer sheets deposited and supported thereon are maintainedin a horizontal plane at a substantially constant elevation as saidsupport members move between said actuated and retracted positions.